then having the buffer is good. One problem with putting them in the pond,
if you are putting in enough to cover the bottom of the pond is the amount
of debris that will be trapped, and due to poor water circulation the
development of some nasty bacteria.

Anaerobic nitrate consuming bacteria, don't you mean?

In marine aquaria, they do this on purpose. They put as much as 6"
of aragonite (sea shell) sand on the bottom of aquariums, to deliberately
create an anaerobic area that will eat nitrates. This is as opposed to
aerobic bacteria, which /produce/ nitrates.

I agree that particulates may be a problem, though.

C//